Safety Sensor

1. A safety sensor, comprising: a light grid, comprising: a plurality of light transmitters for respectively generating a plurality of light beams, the plurality of light beams being arrayed in a grid pattern; and a plurality of light receivers for respectively receiving the plurality of light beams, wherein a monitored field is defined between the plurality of light transmitters and the plurality of light receivers; at least one first evaluation unit having a first evaluation program; at least one second evaluation unit having a second evaluation program, wherein a two-channel system is formed, wherein the evaluation programs are closed programs tested in accordance with safety regulations or safety standards, with each of the first and second evaluation units being connected to a respective random access memory and with each of the first and second evaluation units having a respective program memory, with a bidirectional communication channel being arranged between the first and second evaluation units; and at least one of the first and second evaluation units having a capability of receiving data and/or signals of a system or of a control and providing further non-safety related outputs or non-safety related additional information for output for automation purposes, wherein a cross-comparison of the evaluation results between the first and second evaluation units is carried out, wherein a user program is stored in at least one of the two program memories and/or in one of the two random access memories, with the at least one of the first and second evaluation units which executes the user program having a memory protection device which is configured to restrict memory access of the user program to a defined memory region within the random access memory, the user program classifying an object moving through the monitored field as safe or non-safe.

2. The safety sensor in accordance with claim 1 , wherein the safety sensor is configured to invoke a memory protection violation program by the one of the first and second evaluation units if an access attempt by the user program to memory regions outside the allowed memory region takes place, with the said one of the first and second evaluation units executing the evaluation program and with the safety sensor being configured to refuse the access to the memory region.

3. The safety sensor in accordance with claim 1 , wherein the safety sensor is configured to assign a part of the random access memory to the user program in the random access memory of the associated one of the first and second evaluation units for use by the evaluation program, with the memory protection device being configured to restrict access of the user program only to this part of the random access memory.

4. The safety sensor in accordance with claim 1 , wherein the safety sensor is configured to execute the user program cyclically by the evaluation program of the one of the first and second evaluation units, with the evaluation program having a higher priority than the user program.

5. A safety sensor, comprising: a light grid, comprising: a plurality of light transmitters for respectively generating a plurality of light beams, the plurality of light beams being arrayed in a grid pattern; and a plurality of light receivers for respectively receiving the plurality of light beams, wherein a monitored field is defined between the plurality of light transmitters and the plurality of light receivers; at least one first evaluation unit having a first evaluation program; at least one second evaluation unit having a second evaluation program, wherein a two-channel system is formed, wherein the evaluation programs are closed programs tested in accordance with safety regulations or safety standards, with each of the first and second evaluation units being connected to a respective random access memory and with each of the first and second evaluation units having a respective program memory, with a bidirectional communication channel being arranged between the first and second evaluation units; and at least one of the first and second evaluation units of the safety sensor through inputs of the safety sensor having a capability of receiving data and/or signals of a system or of a control and providing further non-safety related outputs or non-safety related additional information for output for automation purposes, wherein a cross-comparison of the evaluation results between the first and second evaluation units is carried out, wherein a user program is stored in at least one of the two program memories and/or in one of the two random access memories, with the at least one of the first and second evaluation units which executes the user program having a memory protection device which is configured to restrict memory access of the user program to a defined memory region within the random access memory, the user program classifying an object moving through the monitored field as safe or non-safe, and wherein the evaluation program has a software abstraction layer which provides a selection of operating data of the safety sensor in a memory region readable for the user program.

6. The safety sensor in accordance with claim 5 , wherein data and/or signals are accessible to the user program via the software abstraction layer.

7. The safety sensor in accordance with claim 1 , wherein the evaluation program has a software abstraction layer which accepts results data of the user program from a memory region writable for the user program and outputs them to an interface and/or keeps the results data ready for invoking for an external control.

8. The safety sensor in accordance with claim 1 , wherein the user program can be stored in both program memories or in both random access memories, with both of the first and second evaluation units being configured to execute the user program, with results of the user program being exchangeable between the first and second evaluation units over the communication channel.

9. A method of using a safety sensor, comprising the steps of: providing a light grid, the light grid having a plurality of light transmitters for respectively generating a plurality of light beams, the plurality of light beams being arrayed in a grid pattern, the light grid further having a plurality of light receivers for respectively receiving the plurality of light beams, wherein a monitored field is defined between the plurality of light transmitters and the plurality of light receivers; providing at least one first evaluation unit having a first evaluation program; providing at least one second evaluation unit having a second evaluation program; forming a two-channel system, wherein the evaluation programs comprise closed programs tested in accordance with safety regulations or safety standards, with each of the first and second evaluation units being connected to a respective random access memory and with each of the first and second evaluation units having a respective program memory, with a bidirectional communication channel being arranged between the first and second evaluation units; performing a cross-comparison of the evaluation results between the first and second evaluation units, wherein a user program is stored in at least one of the two program memories and/or in one of the two random access memories, with the at least one of the first and second evaluation units which executes the user program having a memory protection device which restricts memory access of the user program to a defined memory region within the random access memory; classifying an object moving through the monitored field as safe or non-safe; and receiving data and/or signals of a system or of a control and providing further non-safety related outputs or non safety related additional information for output for automation purposes.

10. The method in accordance with claim 9 , wherein, if the user program attempts to access memory regions outside the permitted memory region, a memory protection violation program is invoked by the said one of the first and second evaluation units which executes the evaluation program and the access to the memory region is refused.

11. The method in accordance with claim 9 , wherein a part of the random access memory is assigned to the user program in the random access memory of the associated evaluation unit for use by the evaluation program, with the memory protection device being configured to restrict access of the user program only to this part of the random access memory.

12. The method in accordance with claim 9 , wherein the user program is executed cyclically by the evaluation program of the one of the first and second evaluation units, with the evaluation program having a higher priority than the user program.

13. The method in accordance with claim 9 , wherein the evaluation program has a software abstraction layer which provides a selection operating data of the safety sensor in a memory region readable for the user program.

14. The method in accordance with claim 9 , wherein the evaluation program has a software abstraction layer which accepts results data of the user program from a memory region writable for the user program and outputs them to an interface and/or keeps the results data ready for invoking for an external control.

15. The method in accordance with claim 9 , wherein the user program is stored in both program memories or in both random access memories, and wherein both evaluation units execute the user program, with results of the user program being exchanged between the evaluation units via the communication channel.